Cancer is a major public health problem, accounting for nearly one out of every four deaths in the United States. American Cancer Society, Facts and Figures 2010. Patient prognosis generally improves with earlier detection of cancer. Indeed, more readily detectable cancers such as breast cancer have a substantially better survival rate than cancers that are more difficult to detect (e.g., ovarian cancer).
Though many treatments have been devised for various cancers, these treatments often vary in severity of side effects. It is useful for clinicians to know how aggressive a patient's cancer is in order to determine how aggressively to treat the cancer. For example, most patients with early-stage asymptomatic prostate cancer are treated with radical prostatectomy or radiotherapy and optionally adjuvant therapy (e.g., hormone or chemotherapy), all of which have severe side effects. For many of these patients, however, these treatments and their associated side effects and costs are unnecessary because the cancer in these patients is not aggressive (i.e., grows slowly and is unlikely to cause mortality or significant morbidity during the patient's lifetime). In other patients the cancer is virulent (i.e., more likely to recur) and aggressive treatment is necessary to save the patient's life.
Thus, there is a serious need for novel and improved tools for both diagnosing cancer and predicting cancer recurrence.